Electric conductor



J. W. MARSH. ELECTRIC CONDUCTOR.

(No ModeL) Patented Sept. 5, 1893.

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UNITED STATES PATENT OFFICE.

JOSEPH WV. MARSH, OF PITTSBURG, PENNSYLVANIA.

ELECTRIC CONDUCTOR.

SPECIFICATION forming part of Letters Patent No. 504,398, datedSeptember 5, 1893.

Application filed August 8. 1892. Serial No. 442,421. (No model.)

To all whom it may concern:

Be it known that I, JOSEPH W. MARSH, a citizen of the United States,residing at Pittsburg, county of Allegheny, and State of Pennsylvania,have invented certain new and useful Improvements in Insulated ElectricConductors, fully described and represented in the followingspecification and the accompanying drawings, forming a part of the same.

This invention relates to insulated electric conductors, the objectbeing to provide a paper insulated conductor which shall be moreefficient and durable than those heretofore in use. A common form ofinsulated electric conductor consists of a wire covered with aconsiderable number of layers of paper tape wound closely upon the wireso as to form a thick insulating covering of paper thereon. It has beenfound in practice, however, that the stiff covering thus formed isliable to crack or break open on bending the wire conductor, which isobjectionable in all cases, and especially so in electric light cableswhere air spaces must be avoided. It has also been suggested that apaper insulation be applied by molding a mass of paper pulp or othermoldable paper upon the conductor, but it is evident that, while thiscovering is cheap, light and seamless, it is especially liable to theabove objection of cracking or breaking open on bending.

The object of my invention is to provide a construction of paperinsulated conductor by which the tendency of the paper to break or crackopen shall .be prevented or lessened, and especially to provide aconstruction by which the cracking or breaking open of a molded papercovering on bending shall be prevented. I attain this object by the useof a cushion next the conductor upon which is applied the insulatingcovering, consisting of a comparatively thick covering of paper tapewound thereon, or a covering of paper molded thereon, this cushion beingconstructed so as to yield slightly upon bending of the wire and preventthe cracking of the paper covering. This cushion may be formed of anysuitable material and applied in any suitable manner, but it preferablyconsists of a fibrous covering which is preferably of a soft or loosenature and may be formed of paper, jute, cotton, or other fiber.

In telephone and other uses in which air spaces are desired to reducethe static capacity of the conductor, this cushion may be usedunsaturated, thus forming a low capacity conductor with air spaces aboutthe conductor, but for electric light purposes for which this conductoris especially designed, the cushion will preferably be saturated with amaterial which will remain semi-fluid under all ordinary conditions oftemperature, all air spaces in the cushion being thus filled up,

while at the same time the special function of the cushion in connectionwith the paper covering is retained. For this saturating material, anyof the filling compounds now in common use in cable construction may beemployed, but I prefer to use a compound formed of two products ofhydrocarbon distillation, one hard and the other soft, mixed in suitableproportions. The conductor thus covered, with the cover either saturatedor unsaturated, may be used without other coverings, but I prefer toapply outside the paper covering a protective covering which may be ofwoven or braided material, rubber, pa-

per, or other suitable material, or the common lead sheath will serve assuch protective covering, if applied to a single conductor.

The conductor embodying my invention may be used alone or with anotherconductor to form a pair, or a group of single conductors or pairs maybe combined into a cable and provided with the usual lead sheath forunderground or aerial use.

Referring to the accompanying drawings:-- Figure l is a broken side viewof a conductor embodying my invention, having a cushionof loose fibrousmaterial and a molded paper covering. Fig. 2 is a cross section of thesame. Fig. 3 is a view similar to Fig. 1, showing a low capacityconductor with a braided cushion forming air spaces. Fig. 4: is a crosssection of the same. Fig. 5 shows the couductor of Fig. l with aprotective covering of cotton or similar woven material.

Referring to saiddrawings, a is the condoctor, I) the cushion, and c thepaper insulating covering.

In Figs. 1 and 2, showing my invention as applied to a conductor for usein electric light construction, the cushionb consists of a mass of loosefibrous material such as cotton, or

jute, which is preferably saturated with a filling compound as abovedescribed. The paper-covering c is placed upon this cushion and consistsin the form shown of a body of moldable paper or paper pulp molded uponthe cushioned conductor. It will be understood, however, as abovedescribed, that a covering consisting of a considerable number of layersof paper or paper tape wound upon the cushioned conductor to forminsulation may be used in place of the molded covering and still bewithin my invention, considered broadly, but the molded paper coveringinconnection with the cushion in itself forms a part of the invention. Ifthe conductor is intended for telephone or other uses where air spacesare desirable, the cushion b of Figs. 1 and 2 may be left unsaturated.

The form of the cushion may be varied widely and any material having thenecessary qualities may be used and applied in any suitable manner. Thusin Figs. 3 and 4 I have shown a construction in which the cushion isformed of strands of fibrous material braided uponthe conductor, thiscushion being saturated or unsaturated, as described in connection withthe construction shown in Figs. 1 and 2. The conductors thus covered maybe used either alone or with other conductors without other covering,but I prefer to apply outside the paper covering 0, a protectivecovering which may be of cotton or other braided material, tape, rubber,or any other suitable material. In Fig. 5, I have shown a conductorhaving such a protective covering cl of braided material.

The molded material is preferably applied in the form of paper pulpformed by the usual processes of paper manufacture. A good Manila ropestock is preferably used, and a binding material, such as glue,mucilage, or dextrine added to it.

Any suitable means may be used for molding the paper pulp upon thecushioned conductors, but it will probably be found preferable to use amachine of the class now in common use for covering wires and cableswith rubber or lead, and for making tubing from similar material. Itwill be understood however, that in place of paper pulp, paper in anyother form may be used, so long as it is moldable to form a seamlesscovering, and that it may be applied to and molded upon the conductor inany suitable manner.

What I claim is- 1. An insulated electric conductor having itsinsulating covering of paper supported by a cushion on the conductor,substantially as described.

2. An insulated electric conductor having its insulating covering ofpaper supported by a cushion of fibrous material on the conductor,substantially as described.

3. An insulated electric conductor having, its insulating covering ofpapersupported by a fibrous cushion saturated with a semi-fluidmaterial, substantially as described.

t. An electric conductor having a cushion thereon and a covering ofpaper molded upon said cushion, substantially as described.

5. An electric conductor having a cushion of fibrous material thereonand a paper covering molded on said fibrous material, substantially asdescribed.

6. An electric conductor having a cushion of fibrous material thereonsaturated with a semi -fluid material, and a paper covering molded onsaid fibrous covering, substantially as described.

7. An electric conductor having a cushion thereon, a paper coveringmolded on said cushion, and a protective covering outside said papercovering, substantially as de scribed.

In testimony whereof I have hereunto set my hand in the presence of twosubscribing witnesses.

JOSEPH IV. MARSH.

Witnesses:

F. A. RINEHART, 0. ROBERT EBEL.

